Electrical condenser



Sept. 1, 1931. w. DUBILIER 1,821,055

ELECTRICAL CONDENSER Filed June 1o, 1924 INVENTOR MMM/r1 ,00a/UER iATTORNEY Patented Sept. 1, 1931 UNITED STATES PATENT OFFICE WILLIAMDUBILIER, F NEW YORK, N. Y., ASSIGNOR lT0 DUBILIER-CONDENSER ICORPORATION, OF NEW YORK, N. Y., CORPORATION OF DELAWARE ELECTRICALApplication filed June 10,

I have invented certain improvements in electrical condensers, for usein oscillatory circuits, and especially radio apparatus.

In the manufacture and design of such condensers, particularly when thecapacity of the condenser is tol be constant, sheets or plates ofelectrically conductive material separated by sheets of insulation areoften assembled to form the stack or body of the condenser; and tomaintain the capacity of the condenser at a fixed value, the sheets mustbe held in iirm engagement over their total area. The formation ofcracks or air spaces, caused by the separation of any of the sheets,must be prevented by every possible means, because such cracks orspaces, even if exceedingly minute, with the high frequencies employedin signalling by radio,

' will inevitably give rise to great vaiiatioiis in the effect of thecondenser, and often render the entire apparatus unserviceable.

In the practice Aof this invention, I incor- J porate in the condensersuperior and effective means for keeping the stack tightly compressed,and for distributing the force of compression with the greatest'uniformity over the area of the stack. Thus interior displacements andthe occurrence of spaces or voids in the stack betweenthe sheets arewholly prevented.

The nature of the invention is set forth in the following descriptionand the accompanying drawings, which disclose one or more constructionsin which the principle of my invention is embodied. Of course, vIreserve the right to Amake changes that come within the scope of theinvention as defined by the broad terms of the appended claims.

On the drawings, Figure l 1s an end .v1ew of one form of a condenseraccording to my invention;

Figure 2, a longitudinal section thereof;4

Figure 3, a similar section of another form of condenser; and ,A

Figure 4, a top plan of the condenser of Figure 3.

On the drawings, the same numerals iden? tify the same parts throughout.

VThe improvedcondensei, as shown in Fig- 54) ures 1 and 2, comprises astack or body 1,

CONDENSER 1924. Serial No. 719,114.

consisting of thin plates or sheets of some electrically conductivematerial, such as metal foil 2, separated by insulation, such as sheetsof mica 3. The top and bottom plates of the stack 1 are, of course, ofinsulation, and the stack is encircled-by a band clamp 4. This clamp 4extends over substantially the Whole of one face of the body and is bentagainst the sides, with its extremities turned down upon the oppositeface, this opposite `face being covered by a face Aplate 5, with whichthe extremities of the 'clamp make contact along the edges. Under theface plate and against the adjacent face of the stack 1, I place acushion (i of some suitable yielding and resilient material of about thesame size as one of the mica sheets; so that when the clamp istightened, it will force the opposite faces of the stack towards eachother, and through the plate 5 it-will exert suitable pressure upon thecushion 6. I prefer rubber as the best material for the cushion 6,because rubber is uniformly resilient and yielding throughout, andeanjust as easily be compressed in the direction of its thickness, as inthe direction of either its length or breadth. Therefore, when the clamp4 is tightened, the pressure which it Will cause to be. exerted upon thesheets of metal foil and mica will be evenly distributed ovei the entirearea of the sheets of the stack 1. and slight iiiequalities in thebending of the. clamp or in the compression that might otherwise beexerted at various points in the stack, will be compensated, and theresultant compression will be'equalized over the total surface of thestack and the sheets constituting saine.

Figures 3 and 4, which illustrate a modification, show a condensercomprising two face plates, such as a cover plate 7 and a base, plate 8,the latter having extensions 9 at its opposite ends. These cover plates.are of some strong and stili insulating material, such as bakelite;While the face plate 5 above melitioned, is preferably of metal. Thestack 1 lies between -the plates 7 and 8, and to the extensions 9 arefastened clips 10 by means of suitable devices such as eyelet rivets 11;

andcach of these clips has a portion lient up and terminating in aflange 12 which overioa laps the adjacent edge of the cover plate 7 Onone face of the stack and directly beneath either the plate 7 or on theplate 8, I place a cushion 6 as before, and around the two plates is aband clamp 13, which lies against the top plate and is bent down acrossthe sides and over upon the outer surface of the base plate 8. Theextremities of the clips 10 may have conductor fastening lugs la. Inthis type of condenser, both the clamp 13, and the, clips l0 are causedto engage the plates tight? ly, the clamp forcing the two plates 7 and 8towards each other, and the clips pressing down the ends of the plate 7.In this construction, the cushion 6 can be compressed to a greaterextent, and not merely beneath the clamp 13.but along its edges also.

Of course, half of the sheets of foil 2 are of one polarity, and theother half are of opposite polarity. The ends of the two groups ofsheets of foil of different polarity are shown as projecting out at theends of the condenser, in Figure 2, to be united to the terminals of anelectric circuit, and in Figures 3 and 4, the sheets of foil of onepolarity will project out to be secured beneath the ad'acent clip 10;the remaining sheets of di erent polarity projecting out over theopposite extension 9 to be secured beneath the other clip 10, and thecondenser can be put in circuit by joining electrical conductors to theclips by means of the lugs 14, or by fastening them with or withoutscrews to theeyelet rivets 11. Of course 1n practice the sheets 2 and 34can be made as thin or as thick as desired, and the condensers in anyrequired sizes.

Having described my invention, what I believe to be new and desire tosecure and protect by Letters Patent of the United States is :e-

1. A condenser comprising a pair of face plates, a stack consisting ofsheets of electrically conductive material separated by 1nsulationbetween said plates, one of said plates having extensions at itsoppositeends, clips secured to said extensions and engaging the adjacent edgesof the other plate, a clamp embracing the condenser and lying betweensaid clips, and a plane cushion of uniformly yieldable and resilientmaterial disposed against oneface of the stack, to cooperate with theclamp and enable pressure to be exerted evenly over the entire area ofthe sheets of conductive material and insulation when said clamp andsaid clips are tightened.

2. In a condenser structure a body comprising electrically conductiveelements separated by dielectric material, and elastic means in contactwith said stack for maintaining pressure directly on the stack oversubstantially the entire area thereof, whereby the condenser body ismaintained in a state of uniform compression.

3. In a condenser structure a body comprising electrically conductiveelements separated by dielectric material, and a cushioning means incontact with said stack for eX- erting pressure directly on the stack insuch manner that a uniform pressure maintained at each point over theentire area of 'the stack regardless of irregularities in the cushion.

5. A condenser comprising a stack of armature members separated bydielectric material, a layer of uniformly elastic material in contactwith said stack, said layer serving to exert a uniform degree ofpressure over the entire active area of the stack, and clamp ing meansfor maintaining pressure on said elastic material.

6. In a condenser, a body having a pluralty of armature membersseparated by dielectric material and resilient means in contact with thebody for exerting pressure at each point over the area of the bodyadjacent thereto, the pressure exerted at any point being independent ofthe pressure exerted at every other point.

7. A condenser comprising a-body of armature elements separated bydielectric material, a bearing plate for the body, a cushion ofuniformly compressible and resilient material between the bearing plateand body, and clamping means for exerting pressure on the said bearingplate, cushion and body, whereby an even degree of pressure is exertedover the entire active area of the body to maintain constant thecapacity of the condenser.

8. A condenser comprising a stack of armature elements separated bydielectric material, a face plate for the stack, a cushion of uniformlycompressible and resilient material between the face plate and thestack, and a pressure clamp encircling the condenser and cushion andengaging the face plate, whereby an even degree of pressure is exertedover the entire active area of the stack to maintain constant thecapacity of the condenser.

9. A condenser comprising a stack of sheets of electrically conductivematerial separated by dielectric material, a cushion of resilient rubberadjacent said stack, bearing plates enclosing said stack and cushion,and clamping means for exerting pressure on said bearing plates, wherebyan even degree of pressure is exerted over the entire active area of thestack to maintain constant the capacity of the condenser.

10. A .condenser comprising a stack of sheets of electrically conductivematerial separated by dielectric material, a resilent Y rubber cushionadjacent said stack, bearing members enclosing said stack and cushion,and clips secured to one of said bearing members and engaging thedjacent ends of the other bearing member 4whereby an even degree ofpressure is exerted over the entire active area of the condenser stackto maintain constant its capacit In testimony whereof aiix my si nature.

WILLIAM DUBI IER.

